Roll heat treating method



April 7, 1970 J. H. SONEKI ET AL 3,505,133

ROLL HEAT TREATING METHOD INVENTORS .9 Joseph H. Sane/(i Lk Rober/ L.Myers J. H. SONEK] ET AL 3,505,133 ROLL HEAT TREATING. METHOD 6Sheets-Sheet 5 S R O T N E V N l Joseph H. Sane/n Haber! L Myers April7,1970 Original Filed Aug. 4. 1967 April 7, 1970 J, H, so ET AL 3,505,133

ROLL HEAT TREATING METHOD 6 Sheets-Sheet 4 Original Filed Aug. 4, 1967IN VE N TORS Joseph H Soneki Rober/L. Myers April 7, 1970 J. H. SONEKIET ROLL HEAT TREATING METHOD 6 Sheets- Sheet 5 Original Filed Aug. 4,1967 m I I I I I I n I INVENTORS Joseph H Sane/0' Roberf L Myers p -7,1970 J. H. SCVDNEKI ETAL 7 3,505,133

ROLL HEAT TREATING METHOD Original Filed Aug. 4, 1967 6 Sheets-Sheet 6Surface of Rol/ Bore of Roll Zero Stress Compress/'00 INVENTORS JosephH. Sane/r1 Roberf L. Myers United States Patent O 3,505,133 ROLL HEATTREATING METHOD Joseph H. Soneki, Bethlehem, and Robert L. Myers,

Coopersburg, Pa., assignors to Bethlehem Steel Corporation, acorporation of Delaware Application Aug. 4, 1967, Ser. No. 658,403,which is a continuation-impart of application Ser. No. 658,097, Aug. 3,1967, which in turn is a division of application Ser. No. 575,736, Aug.29, 1966. Divided and this application Apr. 9, 1969, Ser. No. 814,688

Int. Cl. C21d 1/06 US. Cl. 148-143 4 Claims ABSTRACT OF THE DISCLOSURE Acarriage, vertically movable with respect to fixed heating and quenchingrings, vertically supports a roll having a bore therein. A coolant isforced upwardly through the bore while the roll is progressively heatedand quenched by driving the roll downwardly through the rings. Afterquenching, the roll is submerged in a coolant and laterally repositionedtherein.

CROSS-REFERENCES TO RELATED APPLICATION This application is a divisionof application Ser. No. 65 8,403, filed Aug. 4, 1967, which is itself acontinuationin-part of application Ser. No. 658,097 now abandoned, filedAug. 3, 1967, which is itself a division of application Ser. No.575,736, filed Aug. 29, 1966.

BACKGROUND OF THE INVENTION This invention relates to the heat treatmentof ferrous metal rolls, and more particularly to a method for hardeningthe outer shell of quench-hardenable steel rolls.

Large steel rolls are usually manufactured by forging steel into thedesired shape and then heat treating the steel shape to impart a highdegree of hardness to the outer shell thereof. In order to obtain thedesired hardness, it is necessary to heat the outer shell to atemperature above the upper critical temperature and then quench theouter shell to convert the microstructure thereof into martensite.

It is desirable for the inner portion of the roll to be tough andductile and as free from stresses as possible. Preferably, the heattreating operation is controlled to insure that the inner portion of theroll is substantially unaffected by the hardening of the outer shell.

Inasmuch as the volume of martensite is different from that of themicrostructure of the unhardened portion of the roll, stresses areintroduced into the roll by the quenching operation. If these stressesare in an unfavorable pattern, premature failure of the roll may occur.

In addition to transformational stresses, i.e., those due to changes inmicrostructure, thermal stresses are induced in the roll due to changesin temperature throughout the body of the roll during the heat treatmentthereof.

It is an object of this invention to provide a method for hardening theouter shell of steel rolls whereby the stress patterns in the hardenedroll are favorable.

Another object of this invention is to provide a method whereby steelrolls can be rapidly and efficiently heat treated.

An additional object of the invention is to provide a method for heattreating steel rolls having a bore therein whereby tensile stresses,whether thermal or transformational in origin, are minimized in themetal adjacent to the bore.

SUMMARY OF THE INVENTION We have discovered that the foregoing objectscan be attained by vertically supporting a roll on a carriage, pro-3,505,133 Patented Apr. 7, 1970 'ice viding means for concurrentlyheating a first annular Zone of said roll and quenching a second,contiguous annular zone of said roll, and by providing additional meansas will hereinafter be described and claimed.

In the preferred embodiment, a coolant, the purpose of which is tominimize any substantial change in the temperature of the metal adjacentto the bore during the hardening of the exterior of said roll, is formedupwardly through the bore of the roll while the roll exterior is beingheated and quenched.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURES l and 2 are front and sideelevations, respectively, of the apparatus of the invention.

FIGURES 3 and 4 are sectional views taken along the lines 33 and 44,respectively, of FIGURE 1.

FIGURE 5 is an enlarged front elevation showing details of the apparatusshown in FIGURE 1, while FIG- URES 6 and 7 are sectional views takenalong the lines 66 and 77, respectively, of FIGURE 5.

FIGURES 8 and 9 are plan and side elevation views, respectively, showingdetails of the invention.

FIGURE 10 is a plan view showing further details of the invention.

FIGURE 11 is an enlarged front elevational of rollholding means, whileFIGURE 12 is a sectional view taken along the lines 12--12 of FIGURE 11.

FIGURE 13 is a graph showing the idecdized stress patterns of rolls heattreated with and without bore cooling.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring more particularly toFIGURES 1 and 2, a framework 10 is disposed above a chamber 12containing a coolant 14, e.g. water. The framework 10 comprises aplurality of columns 16 the upper ends of which are connected bylongitudinal beams 24 and by transverse beams 28. The framework 10 isrigidified by a plurality of trusses, not shown.

As shown in detail in FIGURE 3, intermediate the transverse beams 28 isa plurality of transverse supporting beams 34, 36, 38, 40, 42, and 44.Horizontally mounted on beams 38 and 40 is a bearing plate 46 upon whicha main drive motor 48, a brake 50, and a miter gear unit 52 are mounted.The miter gear 52 is connected, through suitable shafts and couplings tomiter gears 54 and 56. Gear 54 is mounted on a bearing plate 58 disposedacross beams 34 and 36. Gear 56 is mounted on a bearing plate 60disposed across beams 42 and 44.

Affixed to the forward longitudinal beam 24 are supporting means 62 and64 upon which gear reducers 66 and 68, respectively, are mounted. Thegear reducer 66 and 68 are connected to the gears 54 and 56,respectively, by suitable shafts and couplings, and are adapted to drivescrews 70 and 72, respectively. Energization of the motor 48 results inthe synchronous rotation of screws 70 and 72.

Vertically disposed above the chamber 12 are guide members 74 and 76.Similar guide members 78 and 80 are vertically disposed within thechamber 12. Guide members 74 and 78 are provided with beveled bearingsurfaces 82, while members 76 and 80 are provided with flat bearingsurfaces 84. Attached to the base of members 74 and 76 are supports 86for bearings 88 in which the lower ends of the screws 70 and 72 aredisposed.

A carriage 90 is adapted to be driven vertically along the framework 10.The carriage 90 broadly comprises a plurality of vertical members 92,and upper crosshead 94, a lower crosshead 96, and a plurality oftrusses, not shown.

As shown in detail in FIGURE 4, mounted on the upper crosshead 94 aretwo fixed ball nuts 100 each of which threadedly engages one of thescrews 70 and 72. Suitable bearings 102, mounted on each end of theupper crosshead 94, slidably engage the bearing surfaces 82 and 84.

Mounted on the lower crosshead 96 is means 104 for supporting avertically disposed roll 106. Means 104 broadly comprises a main housing108 in which a fluid motor, not shown, is mounted. The fluid motor isadapted to rotate a bottom center post 112 in the housing 108. Thebottom center post 112 is provided with a bore, and has a conical uppersection which is adapted to be disposed in fluid-tight engagement withthe lower end of the bore 116 of the roll 106, said lower end beingbeveled. The bottom center post 112 is provided with a plurality ofholes 118, disposed below the level of the coolant 14, through which thecoolant can flow into the bore of the bottom center post 112. Suitablebearings 117, mounted on each end of the lower crosshead 96, slidablyengage the bearing surfaces 82 and 84.

Disposed between the upper and lower crossheads is a length adjustcrosshead 120. As shown in detail in FIGURES 5, 6 and 7, crosshead 120comprises a horizontal supporting structure 122 upon which a motor 124is mounted. The motor 124 is connected, through suitable shafts,couplings, gears, etc., to a pair of rotatable ball nuts 126 mounted onthe crosshead 120. The ball nuts 126 threadedly engage the screws 70 and72. Suitable bearings 128, attached to each end of the crosshead 120,slidably engage bearing surfaces 82 and 84. Energization of the motor124 results in vertical movement of the crosshead 120 relative to thecarriage 90.

Mounted on the crosshead 120 is means for clamping the upper end of avertically disposed roll. Said means comprises a forwardly-extendinghousing 130 to which an arm 132 is pivotally connected by means ofsleeves 134 journaled on a pin 136. Rigidly aflixed to the arm 132 arebracket plates 138 to which a rod 140 is pivotally connected by means ofa pin 141. The rod 140 is connected to the piston of a hydrauliccylinder .142 which is pivotally supported in the housing 130 by bracketplates 144 and pin 145.

Mounted near the lower end of the arm 132 is a plate 146 provided with ahole 148. Mounted on the rear of crosshead 120 is a hydraulic toggleclamp 150, shown in detail in FIGURE 8, comprising a rod 152 adapted tobe driven through the hole 148 when the pivot arm 132 is in its raisedposition by reason of the retraction of rod 140. The toggle clamp 150provides positive means for maintaining the arm 132 in its raisedposition in the event that the hydraulic cylinder 142 shouldmalfunction.

Mounted on the lower end of arm 132 are clamping elements 154 and 156.Element 154 is rigidly affixed to arm 132 while element 156 is adaptedto pivot about a fixed pivot pin 158. Element 156 is linked to a rod 160connected to the piston of a hydraulic cylinder 162 by links 164 and166. The cylinder 162 is adapted to pivot about a pin 168.

Further mounted on the length adjust crosshead 120 is means for engagingthe upper end of the bore 116 of roll 106. This means comprises abracket 170 supporting a hydraulic cylinder 172. A rod 174 connects thepiston of cylinder 172 to a supporting member 176. Member 176 slidablyengages guides 178 and has a plate (180, containing a hole 182, affixedthereto. Mounted on the rear of crosshead 120 is a hydraulic toggleclamp 184, shown in detail in FIGURE 9, comprising a rod 186 adapted tobe driven through hole 182 when the supporting member 176 is properlypositioned relative to the roll 106.

A cylindrical housing 188 is mounted on the supporting member 176.Slidably disposed within the housing 188 is a cylinder 190. Mounted onthe lower end of cylinder 190 is a second cylinder 192. A tubular-member194 extends axially through cylinders 190 and 192 and is coupled to ahollow truncated conical member 196 which is adapted to be disposed influid-tight engagement with the upper end of the bore 116 of the roll106, said upper end being beveled. Member 196 is connected to a bearingmember 198 adapted to rotate in cylinder 192.

Mounted on the front of housing 188 are bracket plates 200 to which ahydraulic cylinder 202 is afiixed by a pin 203. A rod 204 connects thepiston of cylinder 202 to a bracket 206 affixed to a plate 208 mountedon the cylinder 190. A guide rod 210 is attached to plate 208 anddepends through bearings 212 disposed in supporting member 176. Suitablemeans (not shown) is connected to the cylinder 202 whereby constantpressure is maintained against the roll 106 by conical member 196 duringthe heat treating operation.

The tubular member 194 extends through the plate 208 and bracket 206 andis connected to a rotatable joint 214 to which tubing 216 is attached.The tubing 216 is connected to a suction pump (not shown).

As shown in FIGURE 10, disposed above the coolant 14 is means forconcurrently heating a first annular zone of the roll 106 and quenchinga second, contiguous annular zone of said roll. Said means broadlycomprises an annular heating means, e.g., an induction coil 218 disposedabove an annular quenching ring 220, said heating means and quenchingring being coaxial with said roll and mounted in position by suitablebrackets 221.

Mounted in recesess in one wall of the chamber 12 are bearing plates222, upon each of which one end of an inner rail 224 and an outer rail226 are mounted. The other ends of the rails, each of which contains asloping section intermediate first and second horizontal sections, aremounted on bearing plates 227 disposed in recesses in the opposite wallof the chamber.

A shuttle car 228 is adapted to be driven into and out of the chamber 12along rails 224 and 226. The car 228 is provided with forward wheels 230which engage the outer rails 226 and rear wheels 232 which engage theinner rails 224. The inner rails are offset from the outer rails so thatthe body of the car is always horizontal, regardless of its positionalong the rails. The rear of the car 228 is connected to a rod 234connected to the piston of a hydraulic cylinder 236.

The car 228 comprises means 238 for engaging a collar 240 disposed aboutthe neck of the roll 106. As shown in FIGURES 11 and 12, the collar 240,which is adapted to engage a flange 241 on the neck of the roll 106,broadly comprises an annular structure 242 having an opening 244 thereinthrough which the neck of the roll can pass. The lower portion of thestructure 242 is provided with an inwardly-extending flange 246 havingan offset portion upon which the roll flange 241 can be seated. Thecollar is also provided with a flange 250 having a pair of eyebolts 252aflixed thereto. Disposed in the flange 250 is a spring-loaded pin 254adapted to block the opening 244 when the flange 241 of the roll isproperly seated in the collar 240.

Referring again to FIGURE 10, means 238 comprises a plate 256 having arecess 258 therein adapted to receive the collar 240. An offset 260 inplate 256 provides a shoulder upon which the flange 250 can be seated.The plate 256 is mounted on a supporting structure 262 which dependsbelow the rails 224.

The subject apparatus operates substantially as follows. Initially, i.e.prior to the loading of a roll 106 on the carriage 90, the carriage isdisposed a short distance below its uppermost position, and the lengthadjust crosshead is disposed in a predetermined position along thecarriage 90 dependent upon the length .of the roll 106. Supportingmember 176 is disposed in its retracted position, while cylinder isretracted within its housing 1'88. Pivot arm 132 is held in its raisedposition by toggle clamp 150, and clamping element 156 is disposed inits open position by reason of the retraction of the piston of thehydraulic cylinder 162. In addition, the shuttle car 228 is disposed inits outermost position.

The roll 106 is transported to the subject apparatus by means of a cranewhich engages the eyebolts 252 afiixed to the collar 240 disposed aboutthe neck of the roll. The crane suspends the roll a short distance abovethe bottom center post 112.

The main drive motor 48 is energized to drive the carriage 90 upwardlyuntil the bottom center post 112 is in fluid-tight engagement with thelower end of the bore 116 of the roll. The toggle clamp 150 is nextreleased and the arm 132 driven about its horizontal axis until theclamping element 154 contacts the collar 240. The clamping element 156is then driven into contact with the opposite surfaces .of the collar240* by means of hydraulic cylinder 162.

With the roll supported on the bottom center post 112 and clamped in avertical position, the crane is disengaged from the eyebolts 252. Thesupporting member 176 is then driven horizontally until the conicalmember 196 is axially aligned with the roll 106. The toggle clamp 184 isthen actuated to cause the rod 186 to be driven through the hole 182 inthe plate 180, thereby locking the supporting member 176 in position.

The cylinder 190 is next driven downwardly within its housing 188 untilthe conical member 196 is in fluidtight engagement with the upper end ofthe bore 116 of the roll. With the roll disposed between the bottomcenter post 112 and the conical member 196, the clamping means isreturned to its retracted position. This is accomplished by driving theclamping element 156 into its open position, pivoting the arm 132 intoits horizontal position, and locking the arm in said horizontal positionby actuating the toggle clamp 150.

The carriage 90 is then driven downwardly until the lowest portion ofthe roll is within the confines of the induction coil 218. Next, themotor 110 is energized to cause rotation of the bottom center post 112,which results in rotation of the roll 106. The suction pump then isactuated to draw the coolant 14 through the holes 118 into the bore ofthe bottom center post 112, through the entire length of the bore 116 ofthe roll, and through conical member 196, tubular member 194, rotatablejoint 214 and tubing 216. The coolant 14, the temperature of which ismaintained between about 40 and 47 degrees F. by refrigeration means(not shown), is circulated through the entire length of the bore duringthe heating and quenching operation, the temperature and flow rate ofsaid coolant being sufficient to prevent the temperature of the metaladjacent to the bore from rising above the boiling point of the coolant.During a typical heat treatment, the temperature of the metal adjacentto the bore is maintained at about 100 F. There is no substantial changein the temperature of the metal adjacent to the bore and, consequently,there are no substantial thermal stresses induced therein.

Power, e.g. 6O cycle alternating current, is then supplied to theinduction coil 218 until the outer shell of the roll has reached theproper temperature, said temperature being above the upper criticaltemperature. The time required for the outer shell to reach the propertemperature may, for example, be three to six minutes, depending uponthe circumference of the roll, the design of the induction coil, etc.

The carriage 90 is then driven downwardly at a speed of about 1.5 to 45inches per minute. Simultaneously, the quenching ring 220 is actuated todirect a quenchant onto that portion of the roll previously heated.While this portion of the roll is being quenched, a contiguous annularzone of the roll is being heated by the induction coil 218.

After the uppermost portion of the roll has been quenched, the drivemotor 48 is accelerated to rapidly cause the carriage 90, and hence theroll, to be completely submerged in the coolant 14. The position of thecarriage in the coolant is such that the collar 240 is properly alignedwith the collar-engaging means 238 of the shuttle car 228.

The motor is next de-energized to stop rotation of the bottom centerpost 112 and the roll 106. In addition, the suction pump is shut off tostop the circulation of the coolant 14 through the bore 116.

The roll 106 is then disengaged from the carriage 90 and moved laterallyaway therefrom to a post-quench position in the coolant 14 until thetemperature throughout the body of the roll falls to below thattemperature at which tempering occurs, and preferably until thetemperature of the roll falls to about room temperature. To disengagethe roll, the hydraulic cylinder 236 is first actuated to drive theshuttle car 228 down the rails 224 and 226 until the collar-engagingmeans 238 is directly below the flange 241 of the collar 240. The properposition may be ascertained by means of limit switches attached to therails 224 and 226. Next, the carriage 90 is driven downwardly a shortdistance, e.g. approximately ten inches, which causes the bottom centerpost 112 to disengage from the bore 116 of the roll and, at the sametime, causes the cylinder to be driven upwardly within its housing 188.The cylinder 190 is then driven further upwardly to bring the conicalmember 196 out of contact with the bore 116 and beyond the confines ofthe collar 240. The shuttle car 228 is then driven outwardly to thepost-quench position by retracting the rod 234 of the hydraulic cylinder236. The roll is suspended from the collar 240 while still immersed inthe coolant in said post-quench position.

After the temperature of the roll 106 has fallen to about roomtemperature, which may take from 10 to 60 minutes, the crane engages theeyebolts 252 of the collar 240 and raises the roll a short distance,e.g. onehalf inch, to unseat the flange 250* from the collarengagingmeans 238. The car 228 is then driven to its outermost position and theroll raised out of the coolant 14.

Rolls heat treated in the above manner by the subject apparatus havefavorable stress patterns. These favorable stress patterns are shown inFIGURE 13, in which three types of stresses induced in rolls are plottedas a function of distance from the roll exterior to the bore of theroll. Curve A shows the stresses in a roll which has been austenitizedthroughout the body thereof and quenched overall, including the bore.Curve B shows the stresses in a roll which has either been: (1)austenitized throughout and quenched, except for the bore; or (2)surface austenitized and quenched, except for the bore. Curve C showsthe stresses in a roll which has been surface austenitized and quenchedwhile the bore was cooled throughout the entire heat treating operation.

It is clear that, in the midwall of a roll, the maximum tensile stressof curve C does not approach the magnitude of the maximum tensile stressof curve A. Furthermore, the tensile stress level in the metal adjacentto the bore in curve C is much lower than in curve B. In each instance,the likelihood of premature failure of a roll heat treated so as to havethe stress pattern of curve C is much less than in the case of rollsheat treated so as to have the stress patterns of either curves A or B.

We claim:

1. A method of heat treating a quench-hardenable ferrous metal rollhaving a bore therein, comprising:

(a) mounting said roll in a vertical position;

(b) progressively heating successive exterior annular zones of said rollabove the upper critical temperature;

(c) progressively quenching the successively heated exterior annularzones of said roll; and

(d) during steps (b) and (c) forcing a coolant through the entire lengthof the bore of the roll to minimize any change in the temperature of themetal adjacent 7 S to the bore during the hardening of the exterior ofto prevent the temperature of the metal adjacent to said roll. the borefrom rising above the boiling point of said 2. A method as recited inclaim 1, including the further coolant. step of progressively immersingthe quenched zones in 4. The method as recited in claim 3, in which saida coolant and maintaining them in said coolant until the coolantcomprises Water. temperature throughout the body of said roll is below 0that at which tempering occurs. References Cited 3. A method of heattreating a quenchhardenab1e UNITED STATES PATENTS ferrous metal rollhaving a bore therein, comprising:

(a) mounting said roll in a vertical position; 10 2,619,439 11/1952Renmck 148 145 (b) progressively heating successive exterior annular2,831,789 4/1958 German 148150 zones of said roll above the uppercritical tempera- 3,174,884 3/1965 Semen 148143 ture; (c) progressivelyquenching the successively heated RICHARD DEAN Primary Examiner exteriorannular zones of said roll; and 15 U S C1 X R (d) during steps (b) and(c) forcing a coolant through the entire length of the bore of saidroll, the temper- 148145, 52

ature and rate of flow of said coolant being sufficient

